soc/intel/apollolake: make internal pulls weak for gpio inputs

soc/intel/apollolake: make internal pulls weak for gpio inputs

The internal pulls for gpio_input_pullup() and gpio_input_pulldown()
were using fairly strong pulls. Weaken them so that external pulls
can override the internal ones. This matches the current assumptions
of lib/gpio.c.

BUG=chrome-os-partner:54949
BRANCH=None
TEST=Built and used on reef for memory config.

Change-Id: Ifda1d04d40141325f78db277eb0bd55574994abf
Signed-off-by: Aaron Durbin <adurbin@chromuim.org>
Reviewed-on: https://review.coreboot.org/15558
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Andrey Petrov <andrey.petrov@intel.com>
Reviewed-by: Furquan Shaikh <furquan@google.com>